I tired to install the Y811_A1_UItra_V03_20150828, but nothing happened. Currently I'm using the previous Y810_A1_Ultra_V02_20150521 ROM.Can I update to the new one or Y811 and Y810 models are different? Please advise. Thank you in advance.

Could you send me a step by step tutorial, how to do this? Have tried with the built in OTA updater as local update, but after the update nothing happened and it remained on the old rom. Why don't you enable the new rom as an OTA update? Thanks.